From darkness to light: prospects for therapy for childhood retinal disease

Anthony T Moore

Moorfields Eye Hospital and Institute of Ophthalmology UCL

Retinal dystrophies: pathways to therapy

clinical phenotype

gene mapping

protein function

animal models

Human treatment trials

Clinical trial of gene therapy for early-onset severe retinal degeneration caused by defects in RPE65

UCL

JWB Bainbridge, AJ Smith, SS Barker, S Robbie, R Henderson, K Balaggan, A Viswanathan, GE Holder, A Stockman, N Tyler, S Petersen-Jones, SS Bhattacharya, AJ Thrasher, FW Fitzke, BJ Carter, GS Rubin, AT Moore, RR Ali

and the Moorfields Eye Hospital and UCL Eye Gene Therapy Study Group

Institute of Ophthalmology, University College LondonMoorfields Eye Hospital NHS Foundation Trust, LondonNIHR Biomedical Research Centre for Ophthalmology, University College London and Moorfields Eye Hospital LondonDepartment of Civil and Environmental Engineering , University College LondonMichigan State University, MIInstitute of Child Health, University College LondonTargeted Genetics Corporation, Seattle

Bainbridge J et al N Eng J Med 2008 April [Epub]

Lebers amaurosis• first described 1869• infantile onset rod-cone

dystrophy• 2-3 per 100,000 live births• 5% of congenital blindness• AR inheritance • genetically heterogenous• poor vision from infancy• nystagmus • non-recordable ERG

LCA GenesLCA Genes

CPE290

Lebercilin

RDH12

Courtesy of Professor Birgit Lorenz

RPE65 1p31.2

• 14 exons• Encodes a 65 KD protein within RPE• Crucial to Vit A metabolism in retina• responsible for isomerisation of all-trans

retinol to 11-cis retinol• Mutations cause disease in man (6% LCA)

• mouse knockout• Canine model• Gene therapy rescue in mice and dogs

Phenotype associated with RPE65 mutations

– Infantile onset of visual impairment– Light staring – Profound night blindness– Useful vision at young age– Absent rod function– Residual cone function– Progression to severe visual loss in

late teens– Late cell death

Subject RJ age 21

VA Rt 2/48 (1.38) Lt 2/60 (1.48)

Poor colour vision

Visual field loss

Non recordable ERG

• Single gene loss-of-function defect

• Condition is severe and has predictably poor prognosis

• Window of opportunity for intervention

• Intervention might improve function

• Target RPE cells can be transduced efficiently by rAAV

• Principle is proven in experimental models

• UK human trial funded by 970K grant from Department of Health gene

therapy intiative

RPE65 gene therapy for LCA

• Aim: to determine whether gene therapy for retinal dystrophy caused by RPE65 mutations is safe and effective in humans

• Study design phase I/II open-label single-centre dose-escalation study

• IMP rAAV2.hRPE65p.hRPE65

• Primary outcome safety

• Secondary outcome evidence of visual benefit

Design of clinical trial of RPE65 gene therapy for LCA

Inclusion criteria:

• early-onset severe retinal dystrophy

• missense mutations in RPE65

• between 8 and 30 yrs of age

• in each case, the eye with the worse acuity was selected as the study eye

Exclusion criteria:

• visual acuity better than 20/120 in the study eye

• null mutation in RPE65

• contra-indications for systemic immune suppression

Design of clinical trial of RPE65 gene therapy for LCA

Stage 1 of the trial involved:

• 3 young adults (aged 16 to 30 years) with advanced degeneration

• subretinal injection involving up to 1/3 the total retinal area

Subsequent stages will involve:

• 9 subjects younger than 16 yrs

• dose escalation involving larger areas of the retina

Trial stages and dose-escalation

Baseline characteristics of subjects

Age (yrs

)

Sex Mutation Amino acid change

VA (Log-MAR)

Ref. error

ERG

Rods Cones (30Hz flicker)

Macula (PERG/

Multifocal)

1 23 M Homo-zygous

[1102T>C]

p.Tyr368His 1.16 -3.75/-0.50 x170

No definite respons

e

Residual Undetectable

2 17 F c.[11+5G>

A] +[118G>

A]

Splice site p.Gly40Ser

1.52 +1.50/

-1.00 x 90

Residual

Very reduced

and delayed

(4.0uV;41ms)

Untestable (nystagmus

)

3 18 M c.[16G>T]

+ [499G>T]

p.[Glu6X] + [Asp167Tyr]

0.76 -0.25/-2.00 x 52

No definite respons

e

Very reduced

and delayed

(10uV;42ms)

Undetectable

Subretinal injection of rAAV2.hRPE65p.hRPE65 (1x1011/ml; 1ml)

QuickTime™ and aAnimation decompressor

are needed to see this picture.

Resolution of induced retinal detachment

# 1

# 2

# 3

pre-op +1 day +4 monthsduring surgery

Resolution of induced retinal detachment

scan unrecordable

Pre-op

+1 day +2 days

# 1

# 2

# 3

Adverse events

Transient visual loss (associated with induced retinal detachment)

Mild post operative inflammation

No surgical complications

No immune response to vector or RPE65

Visual acuity following subretinal injection

LogMAR(Snellen)

Baseline 2 months

post-op

4 months

post-op

6 months

post-op

12 months

post-op

#1 Study eye 1.16 (20/286) 1.06 (20/226) 0.98 (20/190) 0.86 (20/145)

Control eye 0.88 (20/150) 0.90 (20/156) 0.68 (20/95) 0.78 (20/120)

#2 Study eye 1.52 (20/662) 1.50 (20/632) 1.58 (20/760) 1.52 (20/662)

Control eye 1.62 (20/833) 1.56 (20/662) 1.52 (20/662) 1.58 (20/760)

#3 Study eye 0.76 (20/115) 0.90 (20/156) 0.80 (20/126) 0.76 (20/115)

Control eye 0.54 (20/69) 0.46 (20/58) 0.40 (20/50) 0.44 (20/55)

Microperimetry

control eye

control eye

control eye

study eye

study eye

study eye

Subject #2 Subject #3Subject #1

Microperimetry: Subject #3; 6 months following surgery

control eyestudy eye

Microperimetry: Subject #3; 6 months following surgery

control eyestudy eye

Microperimetry: Subject #3; 6 months following surgery

control eyestudy eye

Dark-adapted perimetry; change in sensitivity over 6 months

control eye

control eye

control eye

study eye

study eye

study eye

#2

#3

#1

Field of right eye

Field of left eye

Dark-adapted perimetry: Subject #3; 6 months following surgery

control (left) eye

study (right) eye

P<0.01

P<0.05

P<0.1

P>= 0.1

P >= 0.1

P<0.1

P< 0.05

P< 0.01

P< 0.001

Positive slope

Negative slope

Dark-adapted perimetry: Subject #3; 6 months following surgery

control (left) eye

study (right) eye

P<0.01

P<0.05

P<0.1

P>= 0.1

P >= 0.1

P<0.1

P< 0.05

P< 0.01

P< 0.001

Positive slope

Negative slope

Assessment of visually-guided mobility: UCL Pedestrian Accessibility & Movement Environment Laboratory

Assessment of visually-guided mobility

Subject #2 Subject #3Subject #1

4 lux4 lux 4 lux

240 lux240 lux 240 lux

Assessment of visually-guided mobilitySubject #3; 6 months following surgery

4 lux

Visually-guided mobility: Subject #3; 6 months following surgery

• Subretinal vector injection is safe

Conclusions

• Even in advanced retinal degeneration, rAAV2.hRPE65p.hRPE65 can improve vision

• These results support further studies in children with RPE65 defects

Acknowledgements

Andrew Dick and The UK RPE65 Gene Therapy Data Safety Monitoring CommitteeAlan Bird, Andrew Webster and Zdenek Gregor: Moorfields RPE65 Gene Therapy Advisory CommitteeVivien Perry and Moorfields PharmaceuticalsGraeme Black and the Manchester Regional Genetics LaboratoryDavid WongThe patients and their families

The Moorfields Eye Hospital / UCL Eye Gene Therapy Study Group; G.W. Aylward, D. Boampong, C. Broderick, P. Buch, C. Childs, Y. Duran, D. Ehlich, S. Falk, M. Feely, T. Fujiyama, F. Ikeji, V. Luong, A. Milliken, R. Maclaren, P. Moradi, F. Mowat, M. Richardson, C. Ripamonti, A.G. Robson, H. Rostron, I. Russell-Eggitt, P. Schlottmann, M. Tschernutter and N. Wasseem.

FundingUK Department of Health The British Retinitis Pigmentosa Society Special Trustees of Moorfields Eye HospitalThe Sir Jules Thorn Charitable TrustThe European Union (EVI Genoret and Clinigene programmes)

The Wellcome Trust The Medical Research CouncilFoundation Fighting Blindness USAFight for SightThe Ulverscroft FoundationFighting Blindness Ireland

Moorfields Eye Hospital and UCL Institute of Ophthalmology Biomedical Research Centre for Ophthalmology JWBB is a Wellcome Advanced Fellow; AJT is a Wellcome Senior Fellow

UCL